update, its installing drivers at 40%.
There's also no driver for the wifi side of the (was Broadcom, now Cypress) wifi/bluetooth chip in the Pi 400, so you'll need an ethernet cable for networking, or a USB wifi adaptor that has an ARM Windows driver for it, if such a thing exists.
I have tested Win11 on RaspPi4 with both a USB Midi keyboard and a USB sound card with great results. Both worked as one would expect on a regular Win10 machine. My intent is to use this setup to play softsynths/VST instruments and so far this is a go.
This is very good news. Before investing much effort setting up a testing version of Windows on the Pi for practical use, is there news whether the release version of Windows will run on the Pi? What's the time frame over which the testing version will still be available and work?